docs: def main():
      """Parse args (expects source and dest doc directories and snippet source dir)
         read all snippets and then process the input files
         writing out the new versions to the output location"""
  
      parser = argparse.ArgumentParser()
      parser.add_argument("--input_dir", help="The Input file directory", default="doc_templates/")
      parser.add_argument("--output_dir", help="Where to store the processed files", default="current_docs/")
      parser.add_argument("--java_src_dir", help="Where Java snippet source files are located",
                          default="src/test/java/io/improbable/snippet/")
      parser.add_argument("--python_src_dir", help="Where Python snippet source files are located",
                          default="src/test/python/")
      parser.add_argument("--debug", action='store_true', help="Turn on script debugging")
  
      args = parser.parse_args()
      if args.debug:
          logging.basicConfig(level=logging.DEBUG)
  
      snippet_store = {}
      for_all_files_in_dir(args.java_src_dir, lambda x: read_file_snippets(args.java_src_dir + x, snippet_store))
      for_all_files_in_dir(args.python_src_dir, lambda x: read_file_snippets(args.python_src_dir + x, snippet_store))
      stripped_snippet_store = {k: strip_block_whitespace(v) for k, v in snippet_store.items()}
      printd(str(stripped_snippet_store))
      check_output_dir_exists(args.output_dir)
      for_all_in_subdirs(args.input_dir, lambda x: do_rewrites(x,
                                                               args.input_dir,
                                                               args.output_dir,
                                                               stripped_snippet_store))